This invention is in the field of agricultural implements and in particular markers to enable an implement operator to follow a desired path relative to a previous implement pass.
Field markers are used in many farm operations, including seeding, tillage, chemical application and fertilizer application. Field markers generally include a marking device on the end of an arm to make a visible mark on the ground laterally offset from the implement to give the driver a visible guide for spacing the implement on the next pass. The markers can include a disc or a tooth which scores a line in the field, or may they may deposit foam, dye, paper or the like on the ground or crop to provide the mark.
With the evolution of wider field equipment field markers are becoming more important as a driving aid to reduce overlaps and misses. Wider implements make it more difficult for the operator to judge accurately the path to drive in order for the implement to follow the correct path with respect to the previous implement path. High input costs for seed, fertilizer, chemicals, fuel and so forth make overlaps costly, and misses provide no return on the implement operation, and lead to further problems, such as weeds, in the future.
Markers have evolved for these wide pieces of equipment where it is not uncommon to have a marker arm reach thirty feet to the side of an implement. Markers are being built strong and heavy to withstand the highly leveraged forces exerted because of the length of these markers, combined with the varying forces on the scoring device, and the variable and often unknown forces resulting from impact with fences, power poles, badger holes, ditches and rough terrain. The marker must also be strong enough to withstand forces inherent due to the markers"" own weight.
These strong and heavy marker arms are expensive and contribute unwanted and sometimes harmful weight and other forces to the outside extremities of the implement they are mounted to. The added weight contributes to implement wings sinking into mud, increased forces required to raise wings for transport, and so forth. Because of the extreme length of the markers, relatively small forces on the outer end of the marker translate to considerable forces that must be absorbed by the mounting apparatus and the implement.
There is considerable prior art in the area, including U.S. Pat. Nos. 6,125,944 and 5,785,128 to Redekop, U.S. Pat. No. 5,542,190 to Wahls, U.S. Pat. No. 5,425,427 to Haugen, and U.S. Pat. No. 5,027,525 to Haukaas. Breakaways using shear pins, bolts, trips or the like are required to allow the marker to move back when it contacts an obstacle, thus avoiding or at least reducing damage from the contact. When the breakaway acts, it is generally required to stop operations and reset the marker in the operating position. Particular breakaways for field markers are disclosed in U.S. Pat. Nos. 5,957,216 to Redekop and 4,825,957 to White et al.
The breakaway of White is particularly addressed to overcoming nuisance failures of conventional breakaways. These nuisance failures occur when the breakaway trips during normal field use when no obstacle is encountered which should cause the breakaway to trip. Such nuisance failures are caused by constant flexing and resulting fatigue of the shear pin or bolt or other mechanism.
A common problem when using present field markers is seeing the furrow scored in the field. Typically a field will have numerous furrows, ridges and so forth that are made by previous operations of various implements. These are often substantially parallel to the mark that the operator is following, with the result that it is difficult to distinguish the mark to be followed from these prior furrows, ridges, and the like.
It is the object of the present invention to provide a field marker that has considerably less weight than conventional markers.
It is a further object of the present invention to provide a marker with a breakaway that resets automatically and that virtually eliminates the nuisance failures common to conventional marker breakaways.
It is a further object of the present invention to provide a marker that scores a mark in the field that is distinguishable from the other furrows and ridges commonly present on the surface of a field.
In a first aspect the invention provides a field marker attachable to an outer end of an agricultural implement for providing a visible mark in the field substantially parallel to a path of the implement and laterally removed from the implement. The marker comprises an arm pivotally attachable at a proximal end thereof to an outer end of the implement at an implement attachment point such that the arm can move up and down to follow contours of the field and such that the arm can move from an operating position, where the arm extends outward from the outer end of the implement, rearward to a retracted position. A marking device is attached at a distal end of the arm and is operative to provide a visible mark in the field below the marking device. An extendable hydraulic cylinder is operatively connected between the implement and the arm such that the hydraulic cylinder moves in a first direction to a stopped position to move the arm to the operating position, and such that the hydraulic cylinder moves in an opposite second direction when the arm moves to the retracted position. An active hydraulic source is operatively connected to the hydraulic cylinder to supply hydraulic fluid to the hydraulic cylinder at an operating pressure such that the hydraulic cylinder remains in the stopped position until a rearward force exerted on the arm causes the pressure of the hydraulic fluid in the hydraulic cylinder to exceed the operating pressures, at which time the hydraulic cylinder moves in the second direction and the arm moves toward the retracted position.
In a second aspect the invention provides a field marker attachable to an agricultural implement for providing a visible mark in the field substantially parallel to a path of the implement and laterally removed from the implement. The marker comprises an arm pivotally attachable at a proximal end thereof to an outer end of the implement at an implement attachment point such that the arm can move up and down to follow contours of the field and such that a distal end of the arm can move from an operating position, where the distal end extends outward from the outer end of the implement, rearward to a retracted position. A marking device is attached at the distal end of the arm and is operative to provide a visible mark in the field below the marking device. An extendable hydraulic cylinder is operatively connected to the arm such that the hydraulic cylinder moves in a first direction to a stopped position to move the distal end of the arm to the operating position, and such that the hydraulic cylinder moves in an opposite second direction when the distal end of the arm moves to the retracted position. An active hydraulic source is operatively connected to the hydraulic cylinder to supply hydraulic fluid to the hydraulic cylinder at an operating pressure such that the hydraulic cylinder remains in the stopped position until a rearward force exerted on the arm causes the pressure of the hydraulic fluid in the hydraulic cylinder to exceed the operating pressure, at which time the hydraulic cylinder moves in the second direction and the distal end of the arm moves toward the retracted position.
Breakaway protection for the field marker is provided by a hydraulic cylinder supplied with hydraulic fluid by an active hydraulic source such as is commonly used to supply hydraulic cylinders to replace springs in various implement applications. The pressure of the hydraulic fluid can be set so that the arm will swing back when only slightly larger than normal forces are encountered, as when striking an obstacle. The arm will automatically return to the operating position when the force on the arm reduces to normal, as when the obstacle is cleared. No pins or trip mechanisms are needed which are subject to wear and fatigue, and so nuisance failures, where the arm moves rearward while in normal operation, are virtually eliminated. If the arm moves rearward in normal operation of the marker of the invention, the pressure of the hydraulic fluid can be increased. Optimum protection of the arm is obtained when the pressure is just high enough overcome the rearward drag exerted by the marking device while operating in normal soil conditions, so that when an obstacle of some kind is encountered, increasing this drag, the arm will move rearward.
A control can be used to vary the operating pressure to suit varying conditions and also to control the speed of movement of the arm. A one way dump valve can allow the arm to move rearwards quickly, and then move back to the operating position slowly, reducing shock forces. The complete operation can be controlled by two simple on-off switches. The operator can choose to activate one marker or both markers at the same time
The field marker of the invention can be built very light and still perform the required functions. The marker can be built economically and does not require the driver to stop to reset or repair the mark arm even after hitting a major obstacle like a power pole. The new marker contributes far less weight to the outside of the implement, and the reduced weight reduces forces exerted on the marker by its own weight.
The same active pressure source can be supplied to the hydraulic cylinder for moving the arm into a transport position. The resulting preset active pressure reduces the risk of damage to the arm if high forces become present for any reason. This further reduces the strength and weight requirements of the arm and again reduces the forces exerted on the implement.
A lift cable can be provided that has its anchor point on its implement end above and offset from the arms pilot. The anchor point and cable are arranged such that the cable becomes loose when the marker is in the operating position to allow the scoring device to contact the ground with gravitational forces. The anchor point and cable are also arranged such that when the arm is pivoted into the stored position, the cable becomes taut and lifts the end of the marker off the ground. The cable length can be adjusted to vary the lifting height. This strong, economic, yet dependable, lifting apparatus further contributes to a marker arm that reduces weight and forces on the equipment.
The marking device can be a single harrow tooth (or similarly fabricated tool) as a scoring device. Such a marking device inherently has less weight and contributes less draft forces than typical disk markers. Alternatively a paper, dye, or foam marker could be used such that no rearward force is normally exerted on the marker.
A light weight caster wheel could be provided at a portion inward from the markers"" outside extremity and set to control the depth and the downward force on the scoring device and thus reduce the draft forces on the marker arm.
In a third aspect the invention provides a field marker attachable to an outer end of an agricultural implement for scoring a visible mark in the field substantially parallel to a path of the implement and laterally removed from the implement. The marker comprises an arm pivotally attachable at a proximal end thereof to an outer end of the implement at an implement attachment point such that the arm extends outward from the outer end of the implement in an operating position where the arm can move up and down to follow contours of the field. A scoring element is attached at a distal end of the arm and is operative to score a visible mark in the field below the scoring element. Means are provided to raise and lower the scoring element such that the scoring element moves down into contact with the field and up out of contact with the field as the marker moves along the field.
Conveniently a wheel supports the arm at an outer portion thereof and the wheel is rotatably attached to an axle at an axis of rotation removed from a center of the wheel such that the scoring element moves down into contact with the field and up out of contact with the field as the marker moves along the field.
As the marker is lifted and lowered, the resulting scored mark is intermittent and makes it easier for the operator to distinguish from continuous lines, such as ridges and furrows, present in the field from other field activities. As the marker is lifted and lowered, residue is better cleared off of the scoring device and there is less overall draft.
Another aspect of the present invention is to provide a marker as previously described that is primarily fabricated using light weight materials such as aluminum, plastics and/or fiberglass. This further reduces the strength and weight requirements of the device and contributes lower adverse forces to the implement.
Using some of the above combinations, large markers can be built that weigh only a fraction of the weight of other markers on the market, as well as significantly reducing forces that are detrimental to the implement to which the markers are mounted.
The present invention can be incorporated with marker arms that are fabricated as a single long arm that folds vertically or horizontally, marker arms that are fabricated to include a telescoping feature as well as a folding feature, and marker arms that are fabricated to include a multitude of folding portions on the arm; such additional folding features may fold portions of the arm vertically or horizontally.